Have you checked the voltage at battery positive and negative terminals while engine running.
Reading should be between 13.2-14.4 voltage. Either lower or higher reading indicates bad battery; bad connection(to ground)
or shorting in wiring.

The required voltage at the batery is a minimum of 13.5 volts and a maxium of 14.5. At idle with lights, A/C and wipers on it has to mantain 13.5 volts. You need to have the battery check and clean your terminals good.